1 2 3 - Torqeedo

Propulsive power and overall efficiency
Propellers on combustion engines of a lower power class cause
some 70% of the motor shaft power to be lost as inefficiency that
cannot be converted to propulsion.
The second important index is the overall efficiency. It describes
the efficiency with which the drive system converts the available
energy sources into output power and is calculated by dividing
the propulsive power by the input power.
Torqeedo builds the most efficient outboards on the market by
far, by means of consistent orientation towards propulsive power
and overall efficiency. As the overall efficiency of a drive system
is given by the product of the partial efficiency levels of all
components, a single poor partial-efficiency level can have a
significant negative influence on overall efficiency. For this
reason, Torqeedo takes great care in the comprehensive
optimization and interaction of all components.
Another commonly used motor index is the static thrust
expressed in kilogram force (kf) or Newton (N). In comparison
to the propulsive power and overall efficiency, this index is less
meaningful, as it only measures propulsion in association with
the static bollard pull experiment. In this case, as the speed is
zero, the effective power (power times speed) is also zero. As a
consequence to this, the static thrust does not provide any
information on the propulsive power that can be actually
achieved and is therefore not a meaningful index when taken in
isolation. It merely serves as an indication for the maximum boat
size that the motor can be used on. Before purchasing a motor, it
is recommendable to test the static thrust specifications
personally. In Torqeedo’s tests of competitor products, the manufacturers’
specified static thrust values could generally not be
reproduced.
Manufacturers‘ specifications and test results of electric boat motors
Product
Maximum
input power
in operation
(electric
motors) in
watts
Maximum
motor shaft
power
(combustion
engines) in
watts
Maximum
propulsive
power in
watts
Maximum
overall
efficiency
of electric
motors in
percent
Maximum
propeller
efficiency of
combustion
engines in
percent
Static
thrust in
kilogram
force
Torqeedo Travel 401 400 175 44 % 18
Torqeedo Travel 801 800 350 44 % 31
Torqeedo Cruise 2.0 2.000 900 45 % 55
Competitor 300 W & 12 V 300 60 20 % 9
Comments
Competitor 500 W & 12 V 500 100 20 % 16 Manufacturer’s specification of static thrust : 25 kf
Competitor 1,000 W & 24 V 1,000 190 19 % 25 Manufacturer’s specification of static thrust : 80 kf
Competitor 2,200 W & 36 V 1,800 600 33 % 40
Competitor 2.3 HP / 4-stroke 1,690 380 22 % 25
Competitor 4 HP / 2-stroke 2,940 700 24 % 32
Competitor 6 HP / 4-stroke 4,410 1,200 27 % 51
A big test for small motors: Accredited test laboratory Potsdam Model
Basin (SVA Potsdam) confirms unique efficiency of Torqeedo outboards.
After successful internal tests and a successful introduction of the
motors onto the market in Germany, Austria and Switzerland, Torqeedo
wanted to have an “ultimate” test and sent two of its outboards to the
SVA Potsdam. The independent experts at the SVA tested and confirmed
the unique overall efficiency level and superior propulsive powers of the
Torqeedo motors under laboratory conditions.
Since its founding more than 50 years ago, the SVA has developed
into an internationally recognized research and consultation facility for
commercial shipbuilding. 45 highly-specialized experts from various
fields as well as test systems and measurement techniques that meet all
international standards consolidate the position of this non-profitmaking
organization as an internationally recognized research center
and accredited test laboratory.
Catalogue 2007